Note: This Instructional Module information comes from our Training Manual. The complete Training Manual can be ordered from our Program and comes with a video, transparency masters, module publications, and many other educational resources.
Module Learning Objectives
Video (See "IAQ Video Sampler" included with the manual)
Additional Video Support
Notes to the Program Leader:This is a suggested teaching plan for a workshop of about 45 minutes on the topic of biological contaminants. If the video "Controlling Mold in the Home" is used in the presentation, the program will be about one hour long. Also, see the "Special Note to the Program Leader" section at the end of this module for optional Stachybotrys information.
The format is a series of masters for making overhead transparencies and a script to accompany each visual. Pull from the "Home IAQ Overview" module the following transparencies with the accompanying script: 5-14. Insert these transparencies in the noted places. You may read the accompanying script or paraphrase in your own style.
Because you will probably get questions about using air cleaners to reduce pollutant levels, read the "Background Q & A" section and the included Rutgers publication dealing with air cleaners in filtration systems. Also, read the rest of the "Background Q & A" section so you can answer other questions.
If the focus of the presentation is on mold and mildew, you can order multiple copies of the publication "Controlling Mold Growth in the Home" from the Publications Office, Kansas State University, Umberger Hall, Manhattan, KS 66506. The video on the "IAQ Video Sampler" may also be ordered from this office. The publication can be used as a handout for the participants. Another publication to hand out to participants is "Biological Pollutants in Your Home," by CPSC and ALA. It is included in this module; it is not copyrighted and may be photocopied.
Because biological pollutants are the main causes of allergies, you
may wish to start the presentation by asking about the allergies participants
are familiar with. Those that are affected by biological contaminants are
allergic to mold, pollen, dust (dust mites), and pets. Then move on to
the first transparency.
BACKGROUND Q AND A
Q. Is it mold?
Smell can be an especially important clue when mold is growing in an area that can not be readily viewed, such as within wall cavities or in heating systems. An additional test that helps to verify the presence of mold is to apply some dilute laundry bleach (chlorine type) to the stain. If it is mold, the color will disappear.
Q. Should I have my home tested for molds?
Is such testing necessary? This is a difficult question to answer. Whatever the type of mold, "a moldy home is not a healthy home," and the mold problem should be corrected. If large areas are contaminated (more than 10 to 20 square feet), it may be worthwhile to test. If there are occupants with high susceptibility to infection (recovering surgical patients, those with reduced immunity or who are taking drugs that suppress the immune system), testing may be warranted. Also, if there is concern about Stachybotrys, which is an especially dangerous mold (see Special Note to the Program Leader section at end of module), testing can identify this.
Testing can warn of potential health problems, and can indicate the degree of safeguards and skill needed in cleanup.
Q. Who does the testing?
Be aware of the limitations and pitfalls of mold testing. A moldy area may contain several varieties of mold; a collected sample may not include all species. Also, some mold types might die off or multiply during transit to the lab, so results may not be entirely representative of what is growing.
Q. Can using air cleaning appliances
remove biological contaminants from the air?
In assessing the potential efficacy of an air cleaner in removing allergens, one should consider the relative contribution of airborne to surface concentrations of the allergens, particularly in the case of pollen and house dust allergens where natural settling may be so rapid that air cleaners contribute little additional effect. Animal dander may settle more slowly, although, again, the surface reservoir far exceeds the amount in the air.
Furthermore, control of the sources of allergens and, where allergens do not originate outdoors, ventilation should be stressed as the primary means of reducing allergic reactions." Consumers who have employed source control and ventilation to reduce contaminants, and who choose to add air cleaning as well, should refer to either of these publications:
The Association of Home Appliances Manufacturers (AHAM) sponsors the Room Air Cleaner Certification Program. The Program provides a uniform and commercially practical verification of the clean air delivery rate (CADR) for tobacco smoke, dust, and pollen removal from the air by a portable air cleaner. The verification testing is provided by an independent laboratory under contract to AHAM.
The CADR is the amount of clean air measured in cubic feet per minute that an air cleaner delivers to a room. AHAM publishes a list of Certified Air Cleaners that meet the standards of the Room Air Cleaners Certification Program. The list contains the CADR ratings for removing dust, tobacco smoke, and pollen by brand name and model number of air cleaners.
The CADR ratings vary greatly by the type of pollutant, as well as by brand and model number. A resident concerned about removing pollen (rather than tobacco smoke, for example) would want to choose an air cleaner certified by AHAM that had a high CADR for pollen. For a copy of the Consumer Guide for Room Air Cleaners, or a list of certified room air cleaners, use AHAM’s fax-on-demand service by calling from a fax machine to 312-984-9950. More information is available on their web page at: http://www.cadr.org/consumer/certified.html
Q. Are air cleaners that use ozone safe and effective?
It may also worsen bronchitis, heart disease, emphysema, and asthma, and can compromise the ability of the body to fight respiratory infections.
Although manufacturers and vendors of ozone generators may describe ozone as "energized oxygen" or "pure air," ozone is a toxic gas with different properties from oxygen. In fact, several federal agencies have established health standards or recommendations to limit human exposure to ozone. Scientific studies have shown that when ozone concentrations do not exceed these public health standards, ozone has little potential to remove indoor air contaminants.
Ozone does not react with some indoor contaminants, or does so only over a period of months. With other chemicals, the reaction with ozone can form harmful or irritating by-products. And particles such as dust and pollen that cause allergies are not removed by ozone. Ozone is also not effective at removing many odor-causing chemicals, nor does it remove viruses, bacteria, mold, or other biological pollutants. Some studies show that ozone concentrations produced by ozone generators can exceed health standards even when one follows manufacturer's instructions.
High concentrations of ozone are sometimes used to help decontaminate unoccupied spaces from certain chemical or biological contaminants or odors, but these should only be used when people are not present. At these high concentrations, not only can ozone be toxic to human health, but can also adversely affect indoor plants and damage materials such as rubber, electrical wire coatings, and fabrics and art work containing susceptible dyes and pigments. The public is advised to use proven methods of controlling indoor air pollution such as: eliminating or controlling pollutant sources, increasing outdoor air ventilation, and using safe, effective methods of air cleaning.
Q. Is vacuuming an effective strategy
for removing biological contaminants that have settled onto surfaces?
Using a cleaner that discharges upward can result in a 35 percent increase in dust in the air. This is because the surface contaminants become airborne through the filter. The vacuum cleaner filter bag retains only the larger particles and allows the smaller ones to pass into the room air.
Some vacuum cleaners are designed with high efficiency particulate air (HEPA) filters that remove at least 99.97 percent of the smallest particles in the discharge air. These are more expensive than most filters. A central vacuum system with the motor, suction blower, and filter bag located in the basement or garage may solve the problems of portable cleaners. There is no air discharge in the room being vacuumed. The filter may be much larger, allowing high efficiency filtration of the vacuum cleaner discharge air with enough air flow to suck imbedded dirt off a carpet.
Q. Does cleaning the ductwork in the home reduce
indoor air contamination?
It is important to keep in mind that dirty air ducts are only one of many possible sources of particles that are present in homes. Pollutants that enter the home both from outdoor and indoor activities such as cooking, cleaning, smoking, or just moving around, can cause greater exposure to contaminants than dirty air ducts. Moreover, there is no evidence that a light amount of household dust or other particulate matter in air ducts poses any risk to your health.
You should consider having the air ducts in your home cleaned if:
EPA does not recommend that air ducts be cleaned routinely, but only
as needed. For more information on choosing a contractor and the methods
of duct cleaning, refer to the EPA publication Should You Have the Air
Ducts In Your Home Cleaned?, included in this module.
Script for Transparency #1
What are the sources of biological pollutants?
Biological pollutants, also called bioaerosols, come from plant and animal material. Some are generated outside the home, such as pollen, but enter the home through open doors and windows and on people and pets entering the home.
Other biological pollutants are generated in the home: mold growth in
the home releases spores into the air; animals generate dander, and insects
generate excrement and body parts that are small enough to become airborne.
Bacteria and viruses are infectious agents that are brought into the home
in a number of ways. All of these pollutants are particulates -- that is,
they are particles so small that they "float" in the air. Larger particles
settle out onto surfaces, but very small particles stay suspended indefinitely.
Script for Transparency #2
Mold growth is almost always due to an excess moisture problem in the
area. Solving the moisture problem will stop the mold growth, although
the existing mold will need to be cleaned up. Solving the moisture problem
can involve some detective work and is not always easy.
Script for Transparency #3
Many places where biological pollutants are found have high humidity levels or moisture associated with them: rooms with humidifiers or unvented combustion space heaters, bathrooms, kitchens, laundry rooms, basements, crawlspaces, and places with water leaks or water damage. Other common sources of moisture include rainwater entry (above or below the ground), groundwater, and insufficient ventilation (house too tight). Places where water collects, such as dehumidifiers, refrigerator collection pans, and air conditioner drip trays, promote the growth of mold and bacteria.
Areas where there is poor ventilation and cold walls, such as unventilated attics and closets, may have mold growth due to condensation. Moist summer air contacting cool, air-conditioned surfaces also creates condensation problems. Mold-contaminated heating and air conditioning systems can spread biological pollutants throughout the house.
Dogs and cats are the sources of allergens for some people. And dust
mites thrive in bedding and upholstery.
Script for Transparency #4
Once the moisture problem has been identified, solving it involves blocking moisture entry, or controlling or removing the source -- repairing rain gutters, for example. Dehumidifiers and air conditioning can lower humidity as well, but these kinds of equipment are expensive to operate and should be considered only after other measures have been tried. Also, check to ensure air conditioning equipment is properly sized. If a unit is too large, cooling will be accomplished and the unit will switch off before adequate dehumidification.
Note to the Program Leader: More information on moisture problems
in the home can be incorporated into the presentation at this point by
using transparencies #5-14 and the accompanying scripts from the "Home
IAQ Overview" module.
Script for Transparency #5
What are the health effects from biological pollutants?
Allergic reactions are the most common health problem associated with biological pollutants. People differ in their sensitivity to biological allergens -- some may have no symptoms, while sensitive persons may have severe health problems. Common symptoms include watery eyes, runny nose and sneezing, nasal congestion, itching, coughing, wheezing and difficulty breathing, headache, dizziness and fatigue.
The most severe reaction to allergens is an asthma attack, which can be life-threatening. The American Lung Association reports there are nearly 10 million people in the U.S. with asthma. Of these, over 2.5 million are children. There are over 4,000 deaths each year from asthma. The number of persons with asthma has been consistently increasing over the last 15 years. Airborne biological pollutants present a special risk to people with allergies and asthma. Note: these pollutants do not cause asthma. Rather, certain pollutants can trigger an attack in people who have asthma.
Infectious diseases caused by bacteria and viruses are generally passed
from person to person through physical contact. Some bacteria and viruses
circulate through indoor ventilation systems.
Script for Transparency #6
How are biological contaminants transported through the house?
Molds and dust mites thrive in similar conditions. Mold grows on organic materials such as paper, textiles, grease, dirt, and soap scum. It requires moisture or high humidity. When a mold colony has been established (for example, on a bathroom wall), it generates mold spores that float through the air, land on other surfaces, and if conditions are right, form new colonies. Mold can also grow in standing water, such as in the reservoirs of humidifiers or dehumidifiers. Mist from some types of humidifiers can spread the mold throughout the house.
Dust mites need a food source of dead human skin cells and high humidity
levels. They often thrive in soft textiles such as bedding, carpet, and
upholstery. When the textiles are disturbed (vacuuming, making beds, or
walking across carpeting), dust mite parts become airborne. Cleaning surfaces
where dust mite particles accumulate can help reduce concentration in the
air. Dust mites have been identified as the single most important trigger
for asthma attacks.
Script for Transparency #7
Pollen and animal dander do not depend on moisture or nutrients in the home as do mold and dust mites. Pollen is plant material usually generated by outdoor plants. It enters the house through open doors and windows, cracks, on shoes and clothing, or can be brought in by pets.
Animal dander is shed by pets and rodents. Like the other particles,
they land on surfaces and become airborne when disturbed.
Script for Transparency #8
Viruses and bacteria grow in appropriate hosts, which include people
and water. They can be spread through indoor ventilating systems. Humidifiers
that are not cleaned and disinfected regularly can have bacteria, as well
as mold, growing in them. The spray from the humidifier causes the contaminants
to become airborne.
How can we test for these contaminants?
It is not practical for a non-professional to test for the presence of biological contaminants. But if contaminants are suspected in the home, an investigation should be conducted to remove and control them because of the health consequences.
Left unchecked, mold can continue to grow and cause health problems for sensitive people. Because there are no standards for "normal" levels of mold, tests are not usually conducted. When tests are done, however, they compare types and levels of molds in the house with molds in the outside air.
Mold growing on surfaces can occasionally be seen (it is sometimes invisible) or smelled (it has a musty odor). Mold should be suspected wherever there are water stains, standing water, or moist surfaces. Conditions that indicate high humidity levels include condensation on windows or walls, water pooled in the basement and crawlspace, rotting wood or other signs of water damage, use of humidifiers, or use of unvented kerosene and gas heaters. Damp carpet, walls feeling cold to the touch, and areas where there is poor ventilation (such as closets) may have mold growth. Cooking or bathing without using an exhaust fan promotes mold growth. Firewood stored in the home can also promote mold growth.
Refrigerator drip pans, humidifiers and dehumidifiers, and the condensate pans in air conditioning units should all be inspected to insure they are not dirty and are not harboring biological pollutants. The Consumer Product Safety Commission (CPSC) recommends regular cleaning of humidifiers and refilling with clean water. Humidifiers should also be treated with a disinfectant (such as chlorine bleach) regularly -- once a week for small humidifiers and every other week for larger ones.
Mold also grows in wall cavities, under carpets, behind wall coverings, above ceilings, and in other places where moisture can accumulate undetected. Before testing for mold, an investigation can be conducted to find building components that are damp or wet.
Many of these same conditions promote the growth of dust mites. However,
dust mites have no smell and cannot be seen. Bedding and other soft textiles
are where dust mites thrive. Whenever pets are in the house, there will
be animal dander. Rodents and other insects (such as cockroaches) can also
be the source of allergens for sensitive people.
Script for Transparency #10
What can be done to control molds?
Keeping surfaces clean and dry is the most effective method of preventing and removing mold. In particular, bathroom surfaces and fixtures should be cleaned to remove soap scum and body oils. Also, running an exhaust fan during and after showering and bathing helps reduce moisture levels.
Other areas of the house should also be kept clean and dry. If carpeting or other furnishings have become wet, they must be dried very quickly and thoroughly to prevent mold growth. Textiles that have been wet for several days cannot often be saved.
Hard surfaces with mold growing on them should be cleaned with a disinfectant,
such as chlorine bleach. Use about 1 cup of chlorine bleach per gallon
of water and dry quickly after cleaning. Textiles should be cleaned in
accordance with label directions.
Script for Transparency #11
If the humidity level in the home remains high, there are several methods for lowering it. When outside air is drier than inside air, opening doors and windows can increase ventilation and help dry out the house. In warm and humid climates, outside air is likely to be more humid than inside air so other strategies must be used.
Dehumidifiers can help lower humidity in rooms or certain areas of the house. They generally are not effective for lowering humidity levels in the whole house. Room-size air conditioners can also help remove moisture from a room or a limited amount of space. Central air conditioning systems are needed to lower humidity levels throughout the house. As mentioned before, air conditioners must be properly sized to lower both temperature and humidity levels.
Crawlspaces can have high humidity levels that promote mold growth. Some building codes require crawlspaces to be ventilated. However, moisture can still migrate from the soil into the crawlspace, so a moisture barrier must be installed to control humidity. Polyethylene sheeting laid on the ground and extending slightly up the sides of the crawlspace can be an effective control. The sheeting can be anchored with sand, bricks, or other weights. Overlap plastic sheets and seal with caulking or tape to prevent ground moisture from entering the crawlspace.
Other moisture problems in basements and crawlspaces can be the result of improper drainage around the foundation. Some problems can be solved with properly functioning gutters and downspouts, and sloping earth away from the house. More severe problems may require installing drain tile systems, sump pumps, or waterproofing basement walls and floors.
Properly installed insulation with a vapor barrier can reduce condensation
problems. Double- or triple-pane windows and storm windows raise the temperature
of inside glass and reduce condensation problems in these areas.
What can be done to control dust mites?
Humidity levels can be lowered using the same methods as for controlling mold. People who are sensitive to dust mites may need to replace carpeting in their homes with hard surface flooring and use area rugs that can be removed and cleaned. Although it is important to vacuum often, filter bags allow small particles to go back into the air and may actually raise dust levels in the air. Vacuums with high efficiency filters and central vacuum systems reduce the airborne dust generated by vacuum cleaning. Allergic people may need to leave the house during vacuum cleaning or may need to wear a dust mask.
Since bedding provides an optimal environment for dust mites to thrive,
wash bedding often with hot water (at least 130o F). Use plastic
coverings on mattresses and pillows. Hard surfaces can be damp cleaned
to remove dust without causing it to become airborne.
Script for Transparency #13
What are other measures to control these contaminants?
General measures for controlling airborne contaminants include maintaining and cleaning heating and air conditioning units, as well as humidifiers and dehumidifiers. Ventilating homes by opening doors and windows may be counter-productive for people allergic to pollens. In homes with ductwork, the standard mesh filter should be replaced with one offering improved performance.
Allergies to pets may be relieved by removing pets from the home or keeping pets out of sleeping quarters. Cats kept in the home should be washed weekly to reduce the allergen level. Allergen accumulation may be reduced with the use of vinyl or hardwood floors instead of carpets. Vacuum with high efficiency filter vacuums or central vacuum systems to remove dusts which may harbor allergens.
Using air cleaning devices may result in lower levels of biological
contaminants. "According to EPA, however, air cleaning alone cannot be
expected to adequately remove all of the pollutants present in the typical
indoor air environment .... The effectiveness of air cleaners in removing
pollutants from the air is a function of both the efficiency of the device
itself and the amount of air handled by the device." Air cleaners are available
in portable tabletop size, room-size consoles, and as part of central heating
and air-conditioning systems in the home. No universally accepted standards
exist for comparing the effectiveness of air cleaning devices. Before purchasing,
consumers should carefully assess any air cleaners being considered.
Script for Transparency #14
In summary, biological contaminants are often responsible for allergic reactions in sensitive people. Reactions can be more severe among people who have asthma. To control the level of biological pollutants:
Optional InformationSpecial Note to the Program Leader (Stachybotrys): At this point, the main workshop material for this module has already been presented. Only use the following script and transparencies about Stachybotrys as an optional resource.
Stachybotrys is one of several molds that can produce potent mycotoxins (toxic agents). According to the New York City Department of Health, people who cleanup widespread fungal contamination may be at risk of severe lung disease. Molds can also cause severe allergic reactions. The most common are runny noses, eye irritation, congestion and aggravation of asthma.
Buildings with mold growth must be remediated as rapidly as possible in order to ensure a healthy environment. Current recommendations are that stachybotrys need not be treated differently than other molds. The use of respiratory protection, gloves, and eye protection is recommended. Extensive contamination (30 or more square feet) should be assessed by an experienced health and safety professional and remediated by personnel with training and experience handling environmentally contaminated material.
A visual inspection is the most important initial step in identifying the size of the area of contamination. Mold testing is not required before remediation. The goal of remediation is to remove or clean contaminated material in a way that prevents the mold from leaving a work area. THE UNDERLYING MOISTURE PROBLEM MUST BE IDENTIFIED AND FIXED!
Children under 12 months old, persons recovering from recent surgery
or people with immune suppression or chronic inflammatory lung diseases
may be at greater risk for developing health problems associated with mold
exposure. Such persons should be removed from the affected area during
Script for Optional Transparency #1
What is Stachybotrys?
Stachybotrys atra (also called S. chartarum) is a black,
slimy mold that grows on wet materials containing cellulose. Such materials
include: paper, wood, cardboard, wallboard, ceiling tiles, drywall, wallpaper,
newspaper, etc. This particular mold contains a toxic substance (called
endotoxin) that can cause serious illness and death in children (especially infants) and adults.
Script for Optional Transparency #2
How can I tell if my house has Stachybotrys?
As was said, this is a black, slimy mold that grows on paper or wood-based products that have been wet for at least several days. There are many other black molds similar in appearance that are not Stachybotrys.
The only way to verify mold identity is by laboratory analysis. Some
experts believe that this mold is not very common in homes; there are other
types of mold that are more common.
Script for Optional Transparency #3
What are the health effects?
In infants, who are especially susceptible, there may be lung hemorrhaging or coughing up of blood; anemia can also be present (although this infection is not the most common cause of anemia).
Symptoms can occur in adults as well, and can include breathing problems, rashes, headache, fatigue and dizziness, nausea, and vomiting and diarrhea.
Even when this mold has stopped growing and has dried out, the toxins
can still be harmful.
Script for Optional Transparency #4
Small areas of mold (less than a couple square feet) can be cleaned
with a solution of 1 cup laundry bleach to a gallon of water. This can
be applied with a sponge or spray bottle, and rinsed after 15 minutes.
Bleach will kill the mold, but does not inactivate the toxin. Be sure to
wear a dust mask, eye protection, and rubber gloves. Provide plenty of
ventilation and keep others out of the work area. To get rid of the mold
for good, it is necessary to solve the moisture or leakage problem. For
larger areas of mold (more than a couple square feet), seek professional
help from the local health department or an environmental firm.
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